Users of a computer system are often required to be registered with the computer system, and must then provide some kind of identification information before being allowed to access the computer system. Identification information may be provided in the form of textual information entered via a keyboard, in the form of information stored on an access token such as a smart card, or in the form of biometric information captured by the system. User registration allows a computer system to control access to its resources, and allows it to provide users with implicit access to their data and preferences as soon as they are identified.